Graphene: IIT and Tor Vergata set world record for solar cell efficiency
Researchers at the Centre for Hybrid and Organic Solar Energy (CHOSE) of the University of Rome “Tor Vergata”, together with researchers at the Italian Institute of Technology (IIT) and the University of Applied Sciences in Crete (TEI), have set the new world record for conversion efficiency of a perovskite photovoltaic module with an area larger than 50 cm2. The success was achieved as part of Graphene Flagship, the European project that can count on an investment of 1 billion euro to promote graphene-based innovation in such sectors as energy, electronics, technology and medicine.
Perovskite is an inorganic crystal that offers numerous advantages in the production of efficient and cost-effective solar cells. The potential of perovskites on photovoltaic modules was demonstrated typically in the laboratory on cells less than 1 cm2 in size, whereas the new test was performed on modules with an area larger than 50 cm2. The electronic and chemical properties offered by graphene have made it possible to overcome the many difficulties related to the realization of large-area perovskite solar panels.
“Scaling the perovskite solar cells – said Aldo Di Carlo of CHOSE, University of Rome “Tor Vergata” – is a critical issue. Beside the quality of the materials, it is mandatory to control the uniformity of the deposition and the quality of interfaces all over the size of the module. For this reason, the introduction of 2D materials that control the interface properties and improve, at the same time, the uniformity of the deposition is a winning strategy that can be easily scaled up at the industrial level”.
In the study – published in the journal ACS Energy Letters – the researchers designed a module consisting of an active perovskite layer and charge transporting layers. To make charge injection more efficient, the interface between perovskite and titania (a material employed in the cell to collect electrons) was improved by adding graphene and exploiting graphene oxide. This resulted in an increased efficiency from 11.6% to 12.6% of a perovskite photovoltaic module with an area of 50.6 cm2. An additional benefit provided by the use of graphene is an increased stability of the perovskite photovoltaic modules: the researchers demonstrated that the modules retained more than 90% of the initial efficiency after 1630 hours.
“The possibility to produce graphene and other 2D materials in ink form is ideal for the realization of thin interfaces between different solar cell components – said Francesco Bonaccorso, a researcher at the Graphene Labs of the Italian Institute of Technology. – This approach significantly improves the performances of solar cells, coupled with the scaling up prospective of inks production and deposition, can boost the commercialization of this technology”.